Patents such as U.S. Pat. Nos. 4,280,498 and 3,039,464 relate to urostomy or ileostomy appliances that may be worn by patients for extended periods (commonly four to seven days) and must therefore be drained periodically. Such an appliance typically lacks the gas vent and filter sometimes found in non-drainable short-term pouches (as disclosed, for example, in U.S. Pat. Nos. 3,084,091, 3,439,677, 3,759,260, and 4,203,445) because of the danger that in a long-term drainable pouch such a filter might become clogged by liquids or solids, resulting in blockage of gas flow from the pouch and possible rupture of the wall thereof, or separation of the adhesive seal against the patient's skin, or leakage through or about the filter element. Therefore, the wearer of a conventional drainable pouch must periodically deflate the pouch, either by cracking open the discharge port, peeling away a portion of the adhesive patch sealing the pouch to the skin surface, or puncturing a hole in the pouch with a pin or other instrument. Such procedures are inconvenient and may lead to additional inconveniences and difficulties. If the pouch is deflated by opening the discharge port, the wearer must also be prepared to cope with the release of liquids from the pouch. Should the bag be deflated by peeling back a portion of the adhesive patch, secure reattachment of the detached portion may be difficult to achieve, and should the wall of the bag be punctured, the hole must then be sealed by tape or other suitable means. All of these procedures require an ostomate to interrupt normal activities and find seclusion to reach the pouch, relieve flatus buildup, and then reseal the pouch to avoid discomfort and embarrassment from escaping odors, fluids, and/or solids.
Other patents relating to vented pouches and illustrative of the art are U.S. Pat. Nos. 3,055,368, 2,054,535, 2,555,086, 3,952,727, and 4,274,848.